Liquid methanol sorption, diffusion and permeation in charged and uncharged polymers

Abstract

Abstract There are few studies of the impact of membrane charge on ion and organic uncharged solute transport in polymers. This study was aimed at addressing the lack of such fundamental information in the literature. Liquid methanol sorption, diffusion and permeation in water swollen, cross-linked, uncharged poly(ethylene glycol) diacrylate (XLPEGDA) and in charged membranes were investigated. Membrane water content significantly influences methanol solubility, diffusivity and permeability, with more swollen membranes having faster methanol transport rates. The Mackie-Meares model was used to interpret and correlate diffusion data. The Flory-Rehner theory for ternary systems was used to interpret methanol sorption isotherms in XLPEGDA-based polymers. Methanol and sodium chloride transport patterns are similar in neutral hydrogels, while substantial differences are observed in ion exchange polymers. These differences are ascribed to sodium chloride transport in charged polymers being strongly influenced by Donnan exclusion, while methanol sorption and diffusion are not.